Heat detector and connector assembly



y 11, 1954 1.. v. HEBENSTREIT HEAT DETECTOR AND CONNECTOR ASSEMBLYFiled'Nov. 8, 1951 Q INVENTOR.

lesfer Vfifielzslreil' a W z d ATTOHNE Y Patented May 11, 1954 HEATDETECTOR AND CONNECTOR ASSEMBLY Lester V. Hebenstreit, Bloomfield, N.J., assignor to Specialties Development Corporation, Belleville, N. J.,a corporation of New Jersey Application November 8, 1951, Serial No.255,483

9 Claims.

The present invention relates to heat and flame detecting devices; and,more particularly, is concerned with heat detector and connectorassemblies of the continuous cable type wherein a pair of electricallyconductive wires are separated by a mass of material which acts as an.insulator at normal temperatures but is rendered electricallyconductive at abnormally high temperatures and wherein the ends of thewires are electrically connected to equipment for detecting the flow ofcurrent therethrough, the material being of the type having negativetemperature coefficient of resistivity characteristics permittingrepeated use thereof.

In constructing such assemblies, it is customary to arrange the Wiresand the so-called thermistor material in a thin heat conductive metallictube and to attach the connectors to the ends of the tube with the wireselectrically connected to the connectors. One of the difficultiesencountered in connection with such assemblies is that moisture may betrapped in or enter the tube, and that such moisture makes the operatingcharacteristics of the heat detecting elements unreliable. For example,under one condition of moisture content current flow may be indicated ata given temperature whereas under another condition of moisture contentcurrent flow may be indicated at a much different temperature. Thus, agiven assembly may vary from time to time to respond at dilferenttemperatures, and there is no assurance that any two assemblies willrespond at the same temperature.

Attempts have been made to control the moisture content, preferably byexcluding moisture, to duplicate operating characteristics and tostandardize the temperature at which assemblies of identicalconstruction will indicate a flow of current, but such attempts havebeen unsuccessful.

Accordingly, an object of the present invention is to provide assembliesof the type indicated herein which are not subject to the foregoingdisadvantages.

Another object is to provide such assemblies which are constructed in amanner to eliminate moisture andto exclude moisture thereafter.

Another object is to provide such assemblies which are reliable inoperation and maintain their operating characteristics during the lifethereof even if repeatedly subjected to abnormally high temperatures andintermittent normal temperatures.

A further object is to accomplish the foregoing in a simple, practicaland economical manner.

Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred, to herein will occur to one skilled in the art upon employmentof the invention in practice.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawing,forming a part of the specification, wherein:

Fig. 1 is an exploded longitudinal sectional view illustrating theelements of an assembly in accordance with the invention prior tosecurement thereof.

Fig. 2 is an enlarged longitudinal sectional view illustrating theelements shown in Fig. 1 in their finally assembled relation to providea heat detector and connector assembly in accordance with the invention.

Fig. 3 is a fragmentary sectional view illustrating a modification ofthe invention.

Referring to the drawing in detail and more particularly to Figs. 1 and2 thereof, there is shown a heat detector and connector assemblygenerally comprising a sleeve ID, a nut H, a split ring l2, a header I4including a pair of terminal tubes IS, a closure IS, a metallic tube I1,and a heat sensitive element in the tube 11 including a pair ofelectrically conductive wires I9 and a mass of material 20 separatingthe wires.

The sleeve I0 is slotted longitudinally at one end thereof to render thesame sufficiently resilient to facilitate insertion into an electricalsocket structure (not shown), and has a circumferential shoulder orflange 2! at about the middle thereof and an annular groove 22 adjacentthe shoulder. The opposite end of the sleeve has a cylindrical section24 of reduced thickness providing an outwardly facing annular shoulder25.

The nut H has an inwardly extending flange 26 adapted to engage theshoulder 2|, and the ring I2 is sprung into the groove 22 to rotatablyretain the nut on the sleeve I6. The nut cooperates with a threadedsection of the socketstructure (not shown) to secure the sleeve thereto.

The header It comprises a cup-shaped metallic shell 21 having an openend formed with an outwardly extending annular flange 29 adapted toacvaees seat on the shoulder of the sleeve and having a closed end wallat the end opposite the open end forming a pair of apertures forreceiving the terminal tubes 15 which are hermetically sealed therein bya bead 28 formed of a glass or other material which is electricallynonconductive and heat resistant. Preferably, the apertures are definedby tubular sections 3| stamped out of the closed end wall and extendinginwardly into the shell to facilitate securement of the terminal tubesand an effective seal between the header and these tubes.

The closure I6 comprises a somewhat conical cover portion 32 having acentral tubular portion 34 extending outwardly therefrom through whichthe heat sensitive element containing tube l! extends, a cylindricalskirt section adapted to extend into the open end of the header shell inclose fitting relation, and an outwardly extending annular flange 36adapted to face the flange 29 of the header. Preferably, the free end ofthe tubular portion 34 is flared outwardly to facilitate passing the endof the tube I"! therethrough.

The tube H and the wires [9 are formed of alloys such as those now knownas Monel and Inconel. The tube ll has an inner diameter of about fiftythousandths of an inch, and has a wall thickness of about fivethousandths of an inch to facilitate bending thereof.

l9 have a diameter of about ten thousandths of an inch.

The mass of material 20 may be in accordance with that disclosed inUnited States Patent No. 2,495,867.

In constructing the heat detector and connector unit shown in Fig. 2,the nut II and the ring l2 are arranged on the sleeve as shown in Fig.1; the header shell 21 and the terminal tubes [5 are secured; and thetube H is inserted into the neck portion and is secured. therein bybrazing or welding to form a hermetic seal between the tube and the neckportion. The core consisting of the wires 19 and the mass of material 20is placed in the tube 11, with ends of the wires separated and thematerial 20 removed therefrom. A copper ringshaped gasket 31 is placedon the flange 36 of the closure, and the closure l 6 and shell 21 areput together, with the gasket between the flanges 29 and 36 and with Theheader shell flange 29 and the closure flange 36 are then brazedtogether to form a hermetic seal therebetween while cooling the terminaltube end of the header to prevent softening of the seal between theterminal tubes and the tubular sections 3| in which they are secured.

The header and closure unit is next dried at a temperature of about 600F. to drive out all traces of moisture while introducing dry gaseousnitrogen at about ten pounds per square inch and maintaining the flow ofnitrogen during the cooling period.

A desiccating unit is applied to the terminal end of the header tomaintain the same in its dry condition, and the terminal tube tips arenow welded to hermetically seal the same and to secure the ends of thewire in electrical connection therewith.

The header is thereafter inserted. into the sleeve as shown in Fig. 2with the header flange 29 resting on the sleeve shoulder 25,. and theThe wires section 24 is crimped over the closure flange 36' to securethese parts in assembled relation.

While the heat detector is shown herein with a connector only at one endthereof for convenience of illustration, the apparatus in accordancewith the present invention as used includes a similar connector at theother end of the heat detector to enable both of the wires iii to beconnected in an electrical circuit including elements for indicating thedetection of abnormal temperatures when the mass 29 becomes conductiveand current flows between the wires.

The advantages of the heat detector and connector unit in accordancewith this invention are:

1. The length of the header permits copper brazing to form a hermeticseal between the shell 21 and the closure I6 without excessively heatingthe beads 28 whereby softening thereof is prevented.

2. The sleeve [0 and the closure [6 are crimped together to form asecond seal around the shell 21 in addition to forming a secureconnection and safe joint between these parts.

3. The connector is so constructed that it fits i standardized socketsand that it meets Army and Navy specifications relating to electricalplug and socket connections.

4. The connector is readily assembled in its construction and can bemade on a mass production basis.

In Fig. 3, a modified unit is illustrated wherein a double walled tube His utilized which comprises an outer tube I1 and an inner tube licoasially arranged in the outer tube in close fitting relation. A brazedjoint 39 is provided within the shell 21 at the junction of its coverportion 32 and its tubular portion 34 which forms a hermetic sealbetween the ends of the tubes Il and Il and between the outer tube Illand the tubular portion 34.

This construction further minimizes leakage of moisture into the sealedunit. For example, even if the outer tube is damaged in a manner to forman opening therein, the inner tube is effective to maintain the hermeticseal about the mass 20, whereby the useful life of the unit isprolonged.

From the foregoing description, it will be seen that the presentinvention provides an improved heat detector and connector assembly ofthe type indicated herein which is simple, durable and conomical inconstruction and is practical and effective in operation and has a longuseful life.

As various changes may be made in the form, construction and arrangementof the parts herein, without departing from the spirit and scope of theinvention and without sacrificing any of its advantages, it is to beinterpreted as illustrative and not in any limiting sense.

I claim:

1. A connector for a metallic tube containing a heat sensing element ofthe class described comprising a metallic cup-shaped member having anopen end and having an aperture the wall facing the open end; a metallicterminal tube extending through said aperture; means hermeticallysealing said tube in said aperture; and a metallic closure member unitedwith said cup-shaped member at its open end to form a hermetic sealtherebetween and having atubular portion extending outwardly from saidcupshaped member adapted to be united with the tube containing the heatsensing element to form a hermetic seal therebetween.

2. A connector for a metallic tube containing a heat sensing element ofthe class described comprising a metallic cup-shaped member of a lengthat least as great as its diameter having an open end and having collarmeans formed with an aperture in the wall facing the open end; ametallic terminal tube extending through said aperture; 2. mass of heatresistive material hermetically sealing said tube in said collar means;and a metallic closure member united with said cup-shaped member at itsopen end to form a hermetic seal therebetween and having a tubularportion extending outwardly from said cupshaped member adapted to beunited with the tube containing the heat sensing element to form ahermetic seal therebetween.

3. A connector for a metallic tube containing a heat sensing element ofthe class described comprising a metallic cup-shaped member having aflange at its open end and having an aperture in the wall facing theopen end; a metallic terminal tube extending through said aperture;means hermetically sealing said tube in said aperture; and a metallicclosure member having means extending into said cup-shaped member tofacilitate assembly of said members having a flange united with saidflange of said cup-shaped member to form a hermetic seal therebetween,and having an elongate tubular portion extending axially outwardly fromsaid cup-shaped member adapted to be united with the tube containing theheat sensing element to form a hermetic seal therebetween, said tubularportion being flared outwardly at the free end thereof.

4. A connector for a metallic tube containing a heat sensing element ofthe class described comprising a metallic cup-shaped member of a lengthat least as great as its diameter having a flange at its open end andhaving an apertured inwardly extending collar section on the wall facingthe open end; a metallic terminal tube extending through said collarsection; a mass of glass hermetically sealing said tube in said collarsection; and a metallic closure member having an annular rim extendinginto said cup-shaped member, having a flange united with said flange ofsaid cup-shaped member to form a hermetic seal therebetween, and havingan elongate tubular portion extending axially outwardly from saidcup-shaped member adapted to be united with the tube containing the heatsensing element to r form a hermetic seal therebetween, said tubularportion being flared outwardly at the free end thereof.

5. A connector for a metallic tube containing a heat sensing element ofthe class described comprising a metallic cup-shaped member having aflange at its open end and having an aperture in the wall facing theopen end; a metallic terminal tube extending through said aperture,means hermetically sealing said tube in said aperture; a metallicclosure member having a flange united with said flange of saidcup-shaped member to form a hermetic seal therebetween and having atubular portion extending outwardly from said cup-shaped member adaptedto be united with the tube containing the heat sensing element to form ahermetic seal therebetween; a sleeve enclosing said cup-shaped memberhaving a shoulder engaged by the flange of said cup-shaped member andhaving an inwardly extending zone engaging the flange of said closuremember; and coupling means mounted on said sleeve.

6. A heat detector and connector assembly comprising a metallic tube; aheat sensitive element in said tube including a pair of electricallyconductive wires and a mass of material separating said wires acting asan electrical insulator at normal temperatures and being adapted to berendered electrically conductive at abnormally high temperatures; ametallic cup-shaped member of a length at least as great as its diameterhaving a flange at its open end and having a pair of apertures in thewall facing the open end; a metallic terminal tube extending througheach of said apertures and each having a wire of said heat sensitiveelement united thereto and being hermetically sealed at the endextending outwardly of said cup-shaped mem ber; means hermeticallysealing each of said terminal tubes in their respective apertures; and ametallic closure member having a flange united with said flange of saidcup-shaped member to form a hermetic seal therebetween and having atubular portion extending outwardly from said cup-shaped member throughwhich said first mentioned tube extends and is united to form a hermeticseal therebetween.

7. A heat detector and connector assembly comprising a metallic tube; aheat sensitive element in said tube including a pairof electricallyconductive wires and a mass of material separating said wires acting asan electrical insulator at normal temperatures and being adapted to berendered electrically conductive at abnormally high temperatures; ametallic cup-shaped member of a length at least as great as its diameterhaving a flange at its open end and having a pair of apertured inwardlyextending collar sections on the wall facing the open end; a metallicterminal tube extending through each of said collar sections and eachhaving a wire of said heat sensitive element extending therein andunited thereto and being hermetically sealed at the end extendingoutwardly of said cup-shaped member; a mass of glass hermeticallysealing each of said terminal tubes in their respective collar sections;and a metallic closure member having an annular rim extending into saidcupshaped member, having a flange united with said flange of saidcup-shaped member toform a hermetic seal therebetween, and having anelongate tubular portion extending outwardly from said cup-shaped memberthrough which said first mentioned tube extends and is united to form ahermetic seal therebetween, said tubular portion being flared outwardlyat the free end thereof.

8. A heat detector and connector assembly comprising a metallic tube; aheat sensitive element in said tube including a pair of electricallyconductive wires and a mass of material separating said wires acting asan electrical insulator at normal temperatures and being adapted to berendered electrically conductive at abnormally high temperatures; ametallic cup-shaped member of a length at least as great as its diameterhaving a flange at its open end and having a pair of apertures in thewall facing the open end; a metallic terminal tube extending througheach of said apertures and each having a wire of said heat sensitiveelement united thereto and. being hermetically sealed at the endextending outwardly of said cup-shaped member; means hermeticallysealing each of said terminal tubes in their respective apertures; ametallic closure member having a flange united with said flange of saidcup-shaped member to form a hermetic seal therebetween and having atubular portion extending outwardly from said cup-shaped member throughwhich said first mentioned tube extends and is united to form a hermeticseal therebetween; a sleeve enclosing said cup-shaped member having ashoulder engaged by the flange of said cup-shaped member and having anin- Wardly extending zone engaging the flange of said closure member;and coupling means mounted on said sleeve.

9. A heat detector and connector assembly comprising an outer metallictube; an inner metallic tube coaxially arranged in said outer tube inclose fitting relation; a heat sensitive element in said inner tubeincluding a pair of electrically conductive Wires and a mass of materialseparating said wires acting as an electrical insulator at normaltemperatures and being adapted to be rendered electrically conductive atabnormally high temperatures; a metallic cup-shaped member of a lengthat least as great as its diameter having a flange at its open end andhaving a pair of apertures in the Wall facing the open 20 end; ametallic terminal tube extending through each of said apertures and eachhaving a wire of said heat sensitive element united thereto and beinghermetically sealed at the end extending outwardly of said cup-shapedmember; means hermetically sealing each of said terminal tubes in theirrespective apertures; a metallic closure member having a flange unitedWith said flange of said cup-shaped member to form a hermetic sealtherebetween and having a tubular portion extending outwardly from saidcup-shaped memher through which said outer tube and said inner tubeextend and to which said outer tube is united to form a hermetic sealtherebetween; and means at the interior of said cup-shaped memberforming a hermetic seal between the ends of said inner and outer tubes.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,282,476 Simon Oct. 22, 1918 2,476,099 Knudsen July 12, 19492,495,867 Peters Jan. 31, 1950 2,586,252 Peters Feb. 19, 1952 2,594,921Hansard Apr. 29, 1952

